Chief prosecutor blames international group of 54 including suspects in Iran, Iraqi and Germany for killings of police.
Bahrain’s king on Monday approved a constitutional amendment granting military courts the right to try civilians.
Military courts in Bahrain were previously limited to trying members of the armed forces or other branches of the security services and could only try civilians under a state of emergency.
Under the new amendment, the courts have the power to try any civilian accused of threatening the security of the state.
The official BNA news agency said on Monday that King Hamad had approved the amendment to Article 105(b) of Bahrain’s constitution.
The move coincided with a decision by the kingdom’s top court to reduce the jail sentence of the leader of main Shia opposition faction, Sheikh Ali Salman, who had been convicted of inciting hatred and insulting the state.
Salman’s sentence was cut from nine years to four years in prison.
The constitutional amendment was approved weeks ago by both the 40-seat upper house of parliament, appointed by the king, and the 40-seat elected lower house.
Authorities have justified the move as necessary to fight what they say are Iran-linked anti-government cells that have targeted the state.
The kingdom accuses the opposition of working with predominantly Shia Iran to incite unrest in the kingdom. Tehran has consistently denied involvement.